BY R. GREIG-SMITH. 



559 



at room temperature (17°). The tests were sealed in capillary 

 tubes and heated at 37° for 30 minutes. Films were made and 

 stained with the Leishman stain. The polynuclear leucocytes 

 were enumerated and the staphylococci contained within were 

 counted. 



In the tabulated results that follow, the phagocytic index means 

 the average number of bacteria englobed by a polynuclear white 

 blood corpuscle, and the numbers within the brackets indicate 

 the total number of the phagocytes that were counted. The 

 brackets following the suspensions show the time during which 

 the serum and suspension were in contact. 



Opsonisation by heated serum. 



Normal saline + suspension + corpuscles 



Normal serum + suspension + corpuscles 



Heated serum + suspension (20 hours at 37' 

 + corpuscles. 



No phagocytosis.* 

 Phagocytosis. Phagocytic 



Index, (22) = 25. 

 Phagocytosis. Phagocytic 



Index, (22) = 25. 



From this experiment it is clear that heating the serum for 15 

 minutes at 60° does not destroy the opsonins, but simply retards 

 their activity. By allowing a sufficient time for the reaction to 

 take place, the opsonisation is complete. 



A second experiment was made two weeks later with the 

 following results. 



This also shows that the opsonin in time recovers from the 

 effect of the heat to which it has been subjected, or to express it 



* In the normal saline test, there were no bacteria within the leucocytes; 

 one or two, here and there, were on the outside of the phagocytes, but as 

 these had evidently adhered in drying the films they were ignored. 



